1. Field of the Invention
The present application relates to a method to produce an optical module that implements a plurality of signal lanes and an optical module produced by the method.
2. Background Arts
An optical transmitter module sometimes causes the optical power exceeding a limit, which is ruled from a viewpoint of, for instance, the eye safety, when a laser diode (LD) installed in the optical transmitter module and provided with an adequate bias current is strongly coupled with an external optical fiber. When the bias current is adjusted or decreased to reduce the optical output power, the LD lowers the resonant frequency, which means that the high frequency performance of the optical transmitter module degrades.
One solution has been proposed; that is, the optical transmitter module shifts the focal point of the LD from the end of the optical fiber. Specifically, when the external optical fiber, which receives the light output from the LD, couples with the optical module by an optical connector, the proposed solution is that the optical connector, exactly, the end of the optical fiber is physically shifted from the focal point of the light output from the LD. The deviation of the end of the optical fiber from the focal point varies a portion of the optical beam entering within the core of the optical fiber, thus, the output power of the light output from the optical fiber may be reduced. This mechanism has been often called as the de-focusing.
In an optical module capable of outputting an optical signal multiplexing a plurality of optical beams depending on wavelengths thereof, the de-focusing above described for one of optical beams may be carried out properly. However, this de-focusing for the one optical beam is not always adequate for rest of the optical beams. Respective optical beams couples with the optical fiber passing respective lanes or optical coupling systems independent of the others. Accordingly, respective optical beams are not always coupled with the optical fiber by a same angle or a same condition for the one of the optical beam subject to the de-focusing.